Editing Multi-exposure HDR capture (section)

=== Storing ===
{{See also|High dynamic range#Storage}}
Information stored in high-dynamic-range images typically corresponds to the physical values of [[luminance]] or [[radiance]] that can be observed in the real world. This is different from traditional [[digital images]], which represent colors as they should appear on a monitor or a paper print. Therefore, HDR image formats are often called ''scene-referred'', in contrast to traditional digital images, which are ''device-referred'' or ''output-referred''. Furthermore, traditional images are usually encoded for the human [[visual system]] (maximizing the visual information stored in the fixed number of bits), which is usually called ''gamma encoding'' or ''[[gamma correction]]''. The values stored for HDR images are often gamma compressed using mathematical functions such as [[power law]]s [[logarithm]]s, or [[floating point]] linear values, since [[Fixed-point arithmetic|fixed-point]] linear encodings are increasingly inefficient over higher dynamic ranges.<ref name="gregward">{{cite web|last=Ward|first=Greg|title=High Dynamic Range Image Encodings|url=http://www.anyhere.com/gward/hdrenc/hdr_encodings.html|work=Anyhere.com|publisher=Anyhere Software}}</ref><ref>{{cite web|title=The Radiance Picture File Format|url=http://radsite.lbl.gov/radiance/refer/Notes/picture_format.html|url-status=dead|archive-url=https://web.archive.org/web/20190128023610/http://radsite.lbl.gov/radiance/refer/Notes/picture_format.html|archive-date=January 28, 2019|access-date=June 12, 2020|work=RadSite.LBL.gov|publisher=[[Lawrence Berkeley National Laboratory]]}}</ref><ref>{{cite book|last=Fernando|first=Randima|url=http://http.developer.nvidia.com/GPUGems/gpugems_ch26.html|title=GPU Gems|date=2004|publisher=Addison-Wesley|isbn=0-321-22832-4|location=Boston|chapter=26.5 Linear Pixel Values|archive-url=https://web.archive.org/web/20100412001848/http://http.developer.nvidia.com/GPUGems/gpugems_ch26.html|archive-date=April 12, 2010|url-status=dead|via=Developer.Nvidia.com}}</ref>

HDR images often do not use fixed ranges per color [[Channel (digital image)|channel]], other than traditional images, to represent many more colors over a much wider dynamic range (multiple channels). For that purpose, they do not use integer values to represent the single color channels (e.g., 0–255 in an 8 bit per pixel interval for red, green and blue) but instead use a floating point representation. Common values are 16-bit ([[half precision]]) or 32-bit [[Floating point|floating-point]] numbers to represent HDR pixels. However, when the appropriate [[transfer function]] is used, HDR pixels for some applications can be represented with a [[color depth]] that has as few as 10 to 12&nbsp;bits ({{#expr:2^10}} to {{#expr:2^12}} values) for luminance and 8&nbsp;bits ({{#expr:2^8}} values) for [[chrominance]] without introducing any visible quantization [[Visual artifact|artifact]]s.<ref name="gregward" /><ref>{{cite web|last1=Mantiuk|first1=Rafal|last2=Krawczyk|first2=Grzegorz|last3=Myszkowski|first3=Karol|last4=Seidel|first4=Hans-Peter|title=Perception-motivated High Dynamic Range Video Encoding|url=http://resources.mpi-inf.mpg.de/hdrvideo/|work=Resources.MPI-Inf.MPG.de|publisher=[[Max Planck Institute for Informatics]]}}</ref>